1. Technical Field
This disclosure generally relates to stickers used to stack lumber for drying, and more specifically relates to an extruded polycarbonate lumber sticker and process for manufacturing the same.
2. Background Art
Lumber is typically sawn from a tree when the tree is green. Green lumber must be dried before it can be used. It is well-known to stack green lumber into layers separated by sticks known in the art as “stickers,” which provide spaces between the layers of lumber that allow the lumber to dry properly. Many different kinds of stickers have been developed and used over the years. The most common stickers are wooden sticks that have a square or slightly rectangular cross-section. The problem with these stickers is they have a limited life and must be replaced after a relatively small number of drying cycles. The typical life of a wood sticker is 8-15 drying cycles.
One type of wooden sticker known in the art is made of Ipê wood (also called Brazilian walnut), which is taken from trees in the rain forests of Central and South America. Stickers made of Ipê wood are used because they are very dense and therefore have a longer life than stickers made of other types of wood, lasting as long as 30-40 cycles. However, the use of Ipê wood for stickers is contributing to deforestation of the Central and South American rain forests. It would be preferable to use other materials for stickers to prevent over-harvesting of certain slow-growth trees, especially those in the rain forests, for wooden stickers.
Many different types of stickers that are made of plastic have been developed. For example, the following United States patents all show various stickers that are made of plastic: U.S. Pat. Nos. 4,788,777; 5,345,695; 6,517,926; and 7,926,199. The stickers in these patents have different configurations, but each has some features that are not desirable, such as being heavier than they need to be, not providing a surface that grips the wood, and having a configuration that required injection molding instead of extruding. Thus, there is a need for a sticker that does not have these undesirable features.